IN NEW YORK CITY, not long ago, perfume bootleggers hatched what they thought was a perfect plot, one that was absolutely undetectable.

Under direction of the gang, a small glass factory turned out imitations of the bottle used by a noted perfumer in selling one of his rare blends at $100 an ounce. Filling these with a cheap substitute, the crooks played their trump card.

Instead of counterfeiting the labels, they bribed the perfumer’s printer and obtained the original plate he had used. As a result, not even the most powerful microscope could find the slightest difference in the exteriors of real and bootleg bottles. The gang thought detection impossible. And it would have been but for a dramatic new weapon recently enlisted in the war against crime.

In his New York City laboratory, Dr. Herman Goodman, skin specialist and a pioneer in this thrilling new method of scientific crime detection, examined bottles brought by the frantic manufacturer.
He carried them to a darkened room, approached a gleaming dome of polished metal, and snapped on a switch. Strange purplish light streamed from the dome. Into this circle of ultra-violet rays, he pushed two bottles, one genuine and one counterfeit. The effect upon the labels was bewildering, fantastic. The slips of paper glowed with a weird light, like the dial of a radium watch. One label shimmered with a bluish tinge, the other with a yellow hue.

IN PRINTING the labels, the gang had used an ink that appeared to the naked eye to be identical with the original. But, under the bombardment of ultra-violet rays, its different chemical composition caused it to glow with a yellow hue, instantly setting the labels apart. By quick examination with an ultra-violet lamp, the perfumer weeded out fake bottles in stores that had been duped, without the costly process of opening each container. Getting the jump on the crooks, he ran the gang to earth before it could sell many of the fake bottles.

This is only one of a score of amazing achievements recently chalked up for this latest crime detector to come from the laboratories of science. The use of rays is the newest thing in criminal hunting. X-rays, piercing through solids to find hidden clues; strange, “one-plane” polarized light, making possible a startling new method of tracing dust and minerals; mysterious ultra-violet ‘black light,” ferreting out evidence through the sheen and glow of common mineralsâ€”these are now major allies of the law.

On a recent 2,000-mile trip, I visited laboratories where white-robed super-sleuths employ these little understood vibrations of the ether to solve baffling crimes. In their darkened chambers, I witnessed the first offensive in a thrilling new attack upon criminals.

All of these rays are formed by electromagnetic vibrations and differ only in wave length. Polarized visible light, the only one of the three seen by human eyes, has the longest wave length; X-rays has the shortest, with ultra-violet falling between.

In the whole world, one authority told me, there are today less than half a hundred detectives trained to capture crooks with these new weapons. Yet, tomorrow, ray-using Sherlocks will be a part of the detective systems throughout the world. Already, a list of their achievements reads like a page from some scientific Arabian Nights.

Take the solution of the “Bandana Murder Case,” in the Middle West, not long ago. Motorists, stopping to change a tire on a side road, discovered a body lying in the ditch, a bullet through the head. There were signs of a struggle, and a single clue, a red bandana handkerchief caught on bushes through which the slayer had escaped.

The victim proved to be a miserly rich man who was foreclosing on farms in the neighborhood. He had many enemies. Threats had been made against him. All those who might have had cause for committing the murder were held on suspicion.

IN THE meantime, the handkerchief, into which grayish lines of dust had been caked by perspiration, moved to the center of the stage. The intelligent chief of police, realizing that the reputations of many men were at stake, took extra precautions and rushed the bandana to another city for examination by an expert.

He followed this scientific sleuth to his laboratory, watched him slip the cloth under an ultra-violet lamp and switch on the rays. Then the amazed officer saw the dust burst into lines of indigo fire. Watching the intense, vivid blue for a moment, the expert turned to him with a single word: “Feldspar.”

Samples of dust from the farms of suspected men were next placed under the rays. They glowed in various hues, most of them showing the presence of feldspar, but none reacting to the light with the exact shade of the bandana particles.

Not far from the scene of the murder, there was a large clay pit from which laborers dug material for a pottery factory. Samples of this clay were placed under the light and burst into the exact sheen of the original dust. A speedy round-up of the workers resulted in the capture of the culprit. He had shot his victim during a struggle in an attempted holdup. As he fled from the scene, the bushes tore the bandana mask from his face and this square of cloth, by the witchery of “black light,” became the dramatic witness that convicted him and freed a number of innocent men.

Of the three “detective rays,” those of ultra-violet are by far the most versatile. Studied seriously only since the war, these vibrations have found a thousand tacks to do. Almost every substance in the world glows, or fluoresces, with a distinctive color when they strike it. At the Scientific Crime Detection Laboratory, in Chicago, I watched white powders turn brilliant orange, vivid purple, blood red when touched by the invisible rays.

IN HIS New York office, Dr. Goodman, who trapped the fake perfumers, showed me 20,000 specimens he has tested in this way. Every color of the rainbow appears, but shades of blue predominate. Why do things fluoresce? That is still a mystery. But the fact that they do is proving of incalculable benefit to the scientific trailer of desperate men.

At the scene of a crime, a bit of leather, a scrap of paper, a single hair may prove the key to a mystery. By using “black light,” as the scientific detectives call ultra-violet rays, the expert can frequently pin such bits of evidence to a suspect. For leather, tanned by different processes, glows in different colors; paper, kept under different storage conditions, fluoresces with varying hues; and hairs that seem the exact shade under ordinary light shine in different colors when exposed to the emanations of ultra-violet.

A few weeks ago, a sensational story was printed. “Scarface” Al Capone, it said, had hired a double, whose face had been cut in exact imitation of the gangster’s, to serve his prison term while he remained in hiding. This fantastic plot, if it were tried, could be exposed in an instant by ultra-violet light, I was told. Old scars, such as Capone’s, fluoresce a dull blue while newer cuts do not.

Bits of glass that appear to have come from the identical windowpane- when viewed in daylight, often glow with various hues under ultra-violet, thus proving their different origin. Early one morning, a milkman in the East found a body lying at the side of the street. It had been hurled there sometime during the night by the machine of a hit-and-run driver.

SCATTERED near the spot were bits of broken glass from the shattered headlight of a car. Not far down the same street, detectives found a machine in a garage with a broken headlight. The glass they had picked up in the street seemed identical with the few fragments still sticking in the frame on the suspected machine. In addition, they learned that the owner had driven in late the night before.

His story was that he had been driving in the country. On a gravel road, he said, a stone was thrown up by a passing car and smashed his headlight. Few people believed that explanation until the glass found near the body and the fragments discovered in the frame were placed in “black light.” Under these rays, the street glass revealed a greenish tinge that the other lacked, removing suspicion from an innocent man by proving positively the scattered bits had come from a different headlight.

By such examination, fake marble can be told from real, imitation silk from the product of silkworms; and in one case, flour found on the clothes of a suspect, which he claimed came from a certain mill, reacted differently to rays from the actual product and proved him a liar.

Even in following the old maxim “Find the woman,” ultra-violet rays may play a part. It has been discovered that hair from the head of a natural blond may fluoresce with a dozen different hues, but that from a bleached blond will always shine with the same bluish glow.

SUPPOSE you found the body of a murdered man lying in a disordered room and under the fingernails of one hand tiny fragments of dark skin, clawed from the assailant during the struggle? How would you use those pieces of skin, no larger than a fly’s wing, to track down the murderer?

That was the problem facing detectives in an Eastern city, a few months ago. They succeeded in capturing the slayer, with hardly another clue, by the use of ultra-violet rays. Was the skin from a negro or a deeply tanned white man? That was the first problem. Experts have discovered a strange fact: the skin of a white man fluoresces under ultra-violet light only when it is not tanned, while the skin of a negro glows only when it is sunburned.

Under “black light,” the minute particles burst into a telltale sheen proving the slayer was a negro who was sunburned. As it was winter at the time, he must have been a recent arrival from the south. On the basis of this clue, the police rounded up all new arrivals and one with a scratched face later confessed to the murder.

SUCH bewildering achievements are not the result of chance. Day by day, scientific detectives in scattered ray laboratories are cataloguing information that the future sleuth will have at his finger tips. All the flours and common industrial dusts of France, for instance, have been studied under ultraviolet light by Edmond Locard, the famous scientific sleuth of Lyon.

At the Scientific Crime Detection Laboratory of Chicago, feathers of birds and minerals of that region are undergoing similar scrutiny. Dr. August J. Pacini, whose Chicago laboratory has reported remarkable achievements in crime solution, is compiling data on poisons studied with rays. In intestines, he has been able to detect small amounts of morphine and mercury compounds by using ultra-violet light and a quartz-lens microscope.

He also reports that the three common narcotics can be told apart instantly by their fluorescence, morphine glowing with a blue sheen, cocaine with a white light, and heroin with a yellow hue.

In Dr. Goodman’s New York laboratory, special study has been made of rouges and cosmetics. Of more than 200 investigated, the fluorescence of many made detection unmistakable. He has also made another discovery that may play an important part in running down clues in some future murder mystery. When manicured nails are seen under ultra-violet light, he reports, the expert can estimate the time that has elapsed since the polish was applied.

PROBABLY the strangest story I heard in the ray laboratories of these modern Merlins concerned the remarkable capture of the “Kissing Bandit” near Chicago. This Don Juan among highwaymen preyed on women returning home after dark. He would relieve them of their money at the point of a pistol, then clap a gloved hand, which left no fingerprints, over their mouths to prevent a scream, and give them a kiss on the cheek as a final flourish to the holdup.

For more than a month, this phantom robber continued to evade the police. Then, one night, the special squad detailed to run him down arrested a well-dressed youth five blocks from the scene of the latest stickup. He protested his innocence, had a good alibi, and was on the point of being released when one of the detectives suggested a novel test.

The suspect’s gloves were taken to a laboratory and placed under an ultraviolet lamp. The watchers saw a queer elongated spot across the palm begin to glow with peculiar brilliance. The girl who had been the victim of the robbery was next placed under the “black light” and the rouge on her lips fluoresced with the precise shade of the spot on the glove. The suspect was held, his activities traced, and he was later sentenced to a long term in prison.

At the Pacini Laboratories, last year, it was announced that different races can be told apart by the fluorescence of teeth and bones. When the pulverized tooth material of Caucasians is placed under ultra-violet rays, Dr. Pacini reports, a greenish glow results. That of Orientals gives a yellow tinge and that of Negroes a red-orange cast.

On August 7, 1930, he was given a chance to prove his theory. Cicero police dragged from the Chicago Drainage Canal the body of a man swollen beyond recognition. The skull had been crushed and the authorities wished to know if the killing was the result of a gang war or a tong outbreak in the Chinese section. So a tooth was submitted to Dr. Pacini. Under his apparatus, the pulverized bone glowed with a yellow hue, showing the victim was an Oriental. Authorities later discovered he had actually been killed in the Chinese quarter and thrown into the canal.

TO AID the modern detective, portable “black light” outfits, that can be plugged into any convenience outlet, are now available. Photographic equipment allows permanent pictures of clues as they appear under ultra-violet rays to be kept on permanent file. One Chicago manufacturer has placed on the market a violet light machine for installing in banks for examining checks and bills.

Erasures in “boosted” checks that are invisible in daylight appear instantly when placed within range of the rays, and counterfeit bills, shining a sickly green in contrast to the snappy blue fluorescence of genuine currency, stand out like a sore thumb. Tracing altered checks with rays, Dr. Goodman, three years ago, caught a skillful criminal who had mulcted one New York organization out of $180,000 in a single year. In a number of European banks, ultra-violet lamps are installed as part of the regular equipment.

Another place where these wonder-working rays have found new employment is in examining letters sent to and from prisoners. Secret writing about escapes or smuggling drugs or firearms becomes visible in black light. Formerly a hot iron was rubbed over suspected letters to bring out the secret words. Now such messages are read and the letter is allowed to go on to confederates outside who are caught when an attempt is made to carry out the plot. One common powder, aesculin, sometimes used in secret inks, responds to rays when it is so dilute there is only one part powder to five million parts water!

AT ONE laboratory, I was shown a check that was signed five years ago with ordinary ink into which a slight amount of this white powder had been dissolved. Under the ultra-violet lamp, this old signature stood out as though written with radium. By thus adding a small quantity of this easily-obtainable powder to the ink in your fountain pen, you can outwit the cleverest forger!

So far, the giants among the detective rays have been those of ultra-violet. But others are important too.

Recently, polarized lightâ€”rays that have passed through prism screens and are vibrating in one direction onlyâ€”has figured in a number of dramatic cases. Used with the petrographic microscope equipped with a special lens, a rare instrument which only a few experts can handle, it is now doing remarkable work in tracing dust and minerals. Seen through this microscope, each mineral has its strange, distinctive pattern or interference figure.

THE greatest triumph for this microscope, and the mysterious “one-way” light which makes its use possible, occurred recently. A middle-western farmer started on an auto trip with his son-in-law. The machine was found overturned on a lonely road, the old man, his skull crushed in, lying at the foot of a bloodstained rock.

The son-in-law, who was uninjured, said he had leaped clear just as the car turned turtle, but that the older man had been thrown from the machine, hitting his head on the rock. This story was accepted until a few days later when it came out that a large amount of accident insurance had just been taken out by the old man.

Authorities investigated. Finally, polarized light, in the hands of an expert with a petrographic microscope, revealed that the overturned car and the bloodstained rock were carefully-planned links in an atrocious crime. Bits of broken rock, extracted from the head of the victim, cast an entirely different pattern from that given by pieces chipped from the bloodstained boulder. Confronted with this evidence, the son-in-law confessed that he had killed his victim.

IF YOU mention the use of rays in crime detection, most people will think of solid-piercing X-rays, which often play a part. In laboratories where these penetrating vibrations stream from glowing tubes, frauds and plots are often exposed. Here, fake paintings are detected and spurious gems revealed. Imitation sapphires and rubies can now be made synthetically so they have the same light refraction, the same chemical composition, and even the same atomic construction as the real gems.

The only way to tell them apart, a German physicist has just announced, is to place them under powerful X-rays from a Coolidge tube. If the stones glow, they are genuine.

In the moat of an ancient fortress near Copenhagen, Danish police, not long ago, found the legless body of a woman. Extensive search among the records of missing persons failed to identify her. The police decided to have the body X-rayed. One lung proved so badly infected with tuberculosis that they concluded the woman must have been a patient at some hospital.

A search of all hospital photographs followed. The X-ray record of one woman’s lung so closely resembled that of the unknown victim that they followed up the clue. When they arrived at the address from which the hospital patient had come for treatment, they learned she had left two weeks before. Undaunted, they examined the furniture and found old fingerprints. These matched exactly those of the murdered woman. Sure of her identity, the police pressed on the trail, found a man with whom she had been associating, and obtained from him a confession.